Fig. 2: ML properties and relative triboelectric series difference (∆S) in inorganic–organic composite ML materials containing the apatite phosphors.
a–c ML spectra, TL glow curves and CL spectra of MPX@PDMS composites (M = Ca/Sr/Ba, X = Cl, luminescent center = Eu). The ML spectra were measured when 80% tensile strain was loaded on the MPX@PDMS films. The TL glow curves were recorded from 100 to 600 K with a fixed heating rate of 50 K/min. Prior to TL measurements, the samples were excited by 365-nm light for 20 s. The CL spectra were obtained by using scanning electron microscopy (SEM) with an electron beam of 7 kV and 60 mA. The ML and CL intensity in (a, c) is normalized to (0, 1). d ML intensity of MPX@PDMS under different tensile strains. e ML intensity of the inorganic–organic composites (IML), triboelectric transfer charge (qP-M), relative triboelectric series difference of the ceramic/organic pairs (∆S), and ML image during the first stretching. MPX [M = C (Ca), S (Sr), B (Ba); X = C (Cl), B (Br)] are abbreviations for M5-x(PO4)3X:Eux phosphors and ZnS is short for ZnS:Mn. Photographs of the inorganic–organic composite films being stretched are inserted in the figure. f Correlation between ∆S and ML intensity in the tested samples. The data presented in (d–f) are shown as the mean ± 2 SD. 3 measurements were performed for each sample to calculate the mean value and SD.
